Dressing with differentially sized perforations

ABSTRACT

A dressing for treating a tissue site may include a base layer, a sealing member, a first and a second wicking layer, and an absorbent layer. The base layer may have a periphery surrounding a central portion and a plurality of apertures disposed through the periphery and the central portion. The apertures in the periphery may be larger than the apertures in the central portion. The sealing member and the base layer may define an enclosure. The first and the second wicking layer may each be disposed in the enclosure with the absorbent layer positioned between the first and the second wicking layer. Other dressings, systems, and methods are disclosed.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/490,918, filed Sep. 19, 2014, which claims the benefit, under 35 USC§ 119(e), of the filing of U.S. Provisional Patent Application Ser. No.61/897,640, entitled “DRESSING WITH DIFFERENTIALLY SIZED PERFORATIONS,”filed Oct. 30, 2013, both of which are incorporated herein by referencefor all purposes.

FIELD

This disclosure relates generally to medical treatment systems and, moreparticularly, but not by way of limitation, to absorbent dressings,systems, and methods for treating a tissue site with reduced pressure.

BACKGROUND

Depending on the medical circumstances, reduced pressure may be usedfor, among other things, reduced-pressure therapy to encouragegranulation at a tissue site, draining fluids at a tissue site, closinga wound, reducing edema, promoting perfusion, and fluid management.Common dressings, systems, and methods may be susceptible to leaks andblockage that can cause a reduction in the efficiency of the therapy ora complete loss of therapy. Such a situation can occur, for example, ifthe amount of fluid in the dressing or system exceeds the fluid capacityof the dressing or system. Further, the formation of condensate in thedressing or system may create similar concerns. Leaks, blockages, andcondensate in the dressing or system may also be perceptible by a userand may lack visual appeal. Prevention of leaks and blockages may beparticularly important when only a limited power supply to the reducedpressure source and other components is available. Thus, improvements todressings, systems, and methods that enhance the management of fluidextracted from a tissue site for increasing reliability, efficiency,visual appeal, and the useable life of the dressing and system aredesirable.

SUMMARY

Shortcomings with certain aspects of tissue treatment dressings,systems, and methods are addressed as shown and described in a varietyof illustrative, non-limiting embodiments herein.

In some embodiments, a system for treating a tissue site may include atissue interface, a dressing, and a reduced-pressure source. The tissueinterface may be adapted to be positioned proximate to the tissue site.The dressing may include a base layer, an adhesive, a sealing member, afirst wicking layer, a second wicking layer, an absorbent layer, and aconduit interface. The base layer may have a periphery surrounding acentral portion and a plurality of apertures disposed through theperiphery and the central portion. The apertures in the periphery may belarger than the apertures in the central portion. Further, the baselayer may be adapted to cover the tissue interface and tissuesurrounding the tissue site. The adhesive may be in fluid communicationwith the apertures at least in the periphery of the base layer. Thesealing member may have a periphery and a central portion. The peripheryof the sealing member may be positioned proximate to the periphery ofthe base layer such that the central portion of the sealing member andthe central portion of the base layer define an enclosure. The firstwicking layer and the second wicking layer may each be disposed in theenclosure. The absorbent layer may be disposed between the first wickinglayer and the second wicking layer. The conduit interface may bepositioned proximate to the sealing member and in fluid communicationwith the enclosure. The reduced-pressure source may be adapted to becoupled in fluid communication with the conduit interface to providereduced pressure to the dressing.

In other embodiments, a dressing for treating a tissue site may includea base layer, an adhesive, a sealing member, a first wicking layer, asecond wicking layer, an absorbent layer, and a conduit interface. Thebase layer may have a periphery surrounding a central portion and aplurality of apertures disposed through the periphery and the centralportion. The apertures in the periphery may be larger than the aperturesin the central portion. The base layer may be adapted to cover thetissue site. The adhesive may be in fluid communication with theapertures in the base layer. The sealing member may have a periphery anda central portion. The periphery of the sealing member may be positionedproximate to the periphery of the base layer such that the centralportion of the sealing member and the central portion of the base layerdefine an enclosure. The first wicking layer and the second wickinglayer may each be disposed in the enclosure. The absorbent layer may bepositioned in fluid communication between the first wicking layer andthe second wicking layer. A peripheral portion of the first wickinglayer may be coupled to a peripheral portion of the second wicking layerproviding a wicking layer enclosure surrounding the absorbent layerbetween the first and the second wicking layer. The conduit interfacemay be positioned proximate to the sealing member and in fluidcommunication with the enclosure.

In other embodiments, a system for treating a tissue site may include atissue interface, a dressing, and a reduced-pressure source. The tissueinterface may be adapted to be positioned proximate to the tissue siteand to distribute reduced pressure to the tissue site. The dressing maybe adapted to provide reduced pressure to the tissue interface and tostore fluid extracted from the tissue site through the tissue interface.The dressing may include a base layer, an adhesive, a sealing member, afirst wicking layer, a second wicking layer, an absorbent layer, and aconduit interface. The base layer may have a periphery surrounding acentral portion and a plurality of apertures disposed through theperiphery and the central portion. The apertures in the periphery may belarger than the apertures in the central portion. The base layer mayadditionally include a border substantially surrounding the centralportion and positioned between the central portion and the periphery.The border maybe free of apertures. The central portion of the baselayer may be adapted to be positioned proximate to the tissue interfaceand the periphery of the base layer may be adapted to be positionedproximate to tissue surrounding the tissue site. Further, the peripheryof the base layer may be adapted to surround the tissue interface, andthe apertures in the base layer may be adapted to be in fluidcommunication with the tissue interface and the tissue surrounding thetissue site. The adhesive may be in fluid communication with theapertures in the base layer. Further, the adhesive may be adapted to bein fluid communication with the tissue surrounding the tissue sitethrough the apertures in the base layer. The sealing member may have aperiphery and a central portion. The periphery of the sealing member maybe positioned proximate to the periphery of the base layer such that thecentral portion of the sealing member and the central portion of thebase layer define an enclosure. The first wicking layer and the secondwicking layer may each be disposed in the enclosure. The absorbent layermay be positioned in fluid communication between the first wicking layerand the second wicking layer. The conduit interface may positionedproximate to the sealing member and in fluid communication with theenclosure. The reduced-pressure source may be adapted to be coupled influid communication with the conduit interface to provide reducedpressure to the dressing.

Other aspects, features, and advantages of the illustrative embodimentswill become apparent with reference to the drawings and detaileddescription that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away view of an illustrative embodiment of a system fortreating a tissue site depicting an illustrative embodiment of adressing deployed at a tissue site;

FIG. 2 is a cut-away view of the dressing of FIG. 1;

FIG. 3 is detail view taken at reference FIG. 3, depicted in FIG. 1,illustrating the dressing of FIG. 1 positioned proximate to tissuesurrounding the tissue site;

FIG. 4A is an exploded view of the dressing of FIG. 1, depicted withouta conduit interface and with an illustrative embodiment of a releaseliner for protecting the dressing prior to application at a tissue site;

FIG. 4B is a plan view of an illustrative embodiment of a base layerdepicted in the dressing of FIG. 4A;

FIG. 5 is a cut-away view of an illustrative embodiment of a fluidmanagement assembly according to the dressing and system of FIG. 1;

FIG. 6 is a cut-away view of another illustrative embodiment of a fluidmanagement assembly according to the dressing and system of FIG. 1;

FIG. 7 is a cut-away view of an illustrative embodiment of a conduitinterface depicted in the dressing of FIG. 1;

FIG. 8 is a cut-away view of another illustrative embodiment of a fluidmanagement assembly suitable for use with the dressing and system ofFIG. 1;

FIG. 9A is a cross-section of an illustrative embodiment of amulti-lumen conduit suitable for use with the dressing and system ofFIG. 1;

FIG. 9B is a cross-section of another illustrative embodiment of amulti-lumen conduit suitable for use with the dressing and system ofFIG. 1;

FIG. 9C is a cross-section of another illustrative embodiment of amulti-lumen conduit suitable for use with the dressing and system ofFIG. 1;

FIG. 9D is a cross-section of another illustrative embodiment of amulti-lumen conduit suitable for use with the dressing and system ofFIG. 1; and

FIG. 9E is a cross-section of another illustrative embodiment of amulti-lumen conduit suitable for use with the dressing and system ofFIG. 1.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following detailed description of non-limiting, illustrativeembodiments, reference is made to the accompanying drawings that form apart hereof. Other embodiments may be utilized, and logical, structural,mechanical, electrical, and chemical changes may be made withoutdeparting from the scope of the appended claims. To avoid detail notnecessary to enable those skilled in the art to practice the embodimentsdescribed herein, the description may omit certain information known tothose skilled in the art. The following detailed description isnon-limiting, and the scope of the illustrative embodiments are definedby the appended claims. As used herein, unless otherwise indicated, “or”does not require mutual exclusivity.

Referring to the drawings, FIG. 1 depicts an embodiment of a system 102for treating a tissue site 104 of a patient. The tissue site 104 mayextend through or otherwise involve an epidermis 106, a dermis 108, anda subcutaneous tissue 110. The tissue site 104 may be a sub-surfacetissue site as depicted in FIG. 1 that extends below the surface of theepidermis 106. Further, the tissue site 104 may be a surface tissue site(not shown) that predominantly resides on the surface of the epidermis106, such as, for example, an incision. The system 102 may providetherapy to, for example, the epidermis 106, the dermis 108, and thesubcutaneous tissue 110, regardless of the positioning of the system 102or the type of tissue site. The system 102 may also be utilized withoutlimitation at other tissue sites.

Further, the tissue site 104 may be the bodily tissue of any human,animal, or other organism, including bone tissue, adipose tissue, muscletissue, dermal tissue, vascular tissue, connective tissue, cartilage,tendons, ligaments, or any other tissue. Treatment of tissue site 104may include removal of fluids, e.g., exudate or ascites.

Continuing with FIG. 1, the system 102 may include an optional tissueinterface, such as an interface manifold 120. Further, the system 102may include a dressing 124, and a reduced-pressure source 128. Thereduced-pressure source 128 may be a component of an optional therapyunit 130 as shown in FIG. 1. In some embodiments, the reduced-pressuresource 128 and the therapy unit 130 may be separate components. Asindicated above, the interface manifold 120 is an optional componentthat may be omitted for different types of tissue sites or differenttypes of therapy using reduced pressure, such as, for example,epithelialization. If equipped, the interface manifold 120 may beadapted to be positioned proximate to or adjacent to the tissue site104, such as, for example, by cutting or otherwise shaping the interfacemanifold 120 in any suitable manner to fit the tissue site 104. Asdescribed below, the interface manifold 120 may be adapted to bepositioned in fluid communication with the tissue site 104 to distributereduced pressure to the tissue site 104. In some embodiments, theinterface manifold 120 may be positioned in direct contact with thetissue site 104. The tissue interface or the interface manifold 120 maybe formed from any manifold material or flexible bolster material thatprovides a vacuum space, or treatment space, such as, for example, aporous and permeable foam or foam-like material, a member formed withpathways, a graft, or a gauze. As a more specific, non-limiting example,the interface manifold 120 may be a reticulated, open-cell polyurethaneor polyether foam that allows good permeability of fluids while under areduced pressure. One such foam material is the VAC® GranuFoam® materialavailable from Kinetic Concepts, Inc. (KCI) of San Antonio, Tex. Anymaterial or combination of materials may be used as a manifold materialfor the interface manifold 120 provided that the manifold material isoperable to distribute or collect fluid. For example, herein the termmanifold may refer to a substance or structure that is provided toassist in delivering fluids to or removing fluids from a tissue sitethrough a plurality of pores, pathways, or flow channels. The pluralityof pores, pathways, or flow channels may be interconnected to improvedistribution of fluids provided to and removed from an area around themanifold. Examples of manifolds may include, without limitation, devicesthat have structural elements arranged to form flow channels, cellularfoam, such as open-cell foam, porous tissue collections, and liquids,gels, and foams that include or cure to include flow channels.

A material with a higher or lower density than GranuFoam® material maybe desirable for the interface manifold 120 depending on theapplication. Among the many possible materials, the following may beused: GranuFoam® material, Foamex® technical foam (www.foamex.com), amolded bed of nails structures, a patterned grid material such as thosemanufactured by Sercol Industrial Fabrics, 3D textiles such as thosemanufactured by Baltex of Derby, U.K., a gauze, a flexiblechannel-containing member, a graft, etc. In some instances, ionic silvermay be added to the interface manifold 120 by, for example, a microbonding process. Other substances, such as anti-microbial agents, may beadded to the interface manifold 120 as well.

In some embodiments, the interface manifold 120 may comprise a porous,hydrophobic material. The hydrophobic characteristics of the interfacemanifold 120 may prevent the interface manifold 120 from directlyabsorbing fluid, such as exudate, from the tissue site 104, but allowthe fluid to pass through.

Continuing with FIG. 1, the dressing 124 may be adapted to providereduced pressure from the reduced-pressure source 128 to the interfacemanifold 120, and to store fluid extracted from the tissue site 104through the interface manifold 120. The dressing 124 may include a baselayer 132, an adhesive 136, a sealing member 140, a fluid managementassembly 144, and a conduit interface 148. Components of the dressing124 may be added or removed to suit a particular application.

Referring to FIGS. 1-4B, the base layer 132 may have a periphery 152surrounding a central portion 156, and a plurality of apertures 160disposed through the periphery 152 and the central portion 156. The baselayer 132 may also have corners 158 and edges 159. The corners 158 andthe edges 159 may be part of the periphery 152. One of the edges 159 maymeet another of the edges 159 to define one of the corners 158. Further,the base layer 132 may have a border 161 substantially surrounding thecentral portion 156 and positioned between the central portion 156 andthe periphery 152. The border 161 may be free of the apertures 160. Thebase layer 132 may cover the interface manifold 120 and tissuesurrounding the tissue site 104 such that the central portion 156 of thebase layer 132 is positioned adjacent to or proximate to the interfacemanifold 120, and the periphery 152 of the base layer 132 is positionedadjacent to or proximate to tissue surrounding the tissue site 104. Inthis manner, the periphery 152 of the base layer 132 may surround theinterface manifold 120. Further, the apertures 160 in the base layer 132may be in fluid communication with the interface manifold 120 and tissuesurrounding the tissue site 104.

The apertures 160 in the base layer 132 may have any shape, such as, forexample, circles, squares, stars, ovals, polygons, slits, complexcurves, rectilinear shapes, triangles, or other shapes. The apertures160 may be formed by cutting, by application of local RF energy, orother suitable techniques for forming an opening. As shown in FIGS.4A-4B, each of the apertures 160 of the plurality of apertures 160 maybe substantially circular in shape, having a diameter and an area. Thearea of each of the apertures 160 may refer to an open space or openarea defining each of the apertures 160. The diameter of each of theapertures 160 may define the area of each of the apertures 160. Forexample, the area of one of the apertures 160 may be defined bymultiplying the square of half the diameter of the aperture 160 by thevalue 3.14. Thus, the following equation may define the area of one ofthe apertures 160: Area=3.14*(diameter/2){circumflex over ( )}2. Thearea of the apertures 160 described in the illustrative embodimentsherein may be substantially similar to the area in other embodiments(not shown) for the apertures 160 that may have non-circular shapes. Thediameter of each of the apertures 160 may be substantially the same, oreach of the diameters may vary depending, for example, on the positionof the aperture 160 in the base layer 132. For example, the diameter ofthe apertures 160 in the periphery 152 of the base layer 132 may belarger than the diameter of the apertures 160 in the central portion 156of the base layer 132. Further, the diameter of each of the apertures160 may be between about 1 millimeter to about 50 millimeters. In someembodiments, the diameter of each of the apertures 160 may be betweenabout 1 millimeter to about 20 millimeters. The apertures 160 may have auniform pattern or may be randomly distributed on the base layer 132.The size and configuration of the apertures 160 may be designed tocontrol the adherence of the dressing 124 to the epidermis 106 asdescribed below.

Referring to FIGS. 4A-4B, in some embodiments, the apertures 160positioned in the periphery 152 may be apertures 160 a, the apertures160 positioned at the corners 158 of the periphery 152 may be apertures160 b, and the apertures 160 positioned in the central portion 156 maybe apertures 160 c. The apertures 160 a may have a diameter betweenabout 9.8 millimeters to about 10.2 millimeters. The apertures 160 b mayhave a diameter between about 7.75 millimeters to about 8.75millimeters. The apertures 160 c may have a diameter between about 1.8millimeters to about 2.2 millimeters. The diameter of each of theapertures 160 a may be separated from one another by a distance Abetween about 2.8 millimeters to about 3.2 millimeters. Further, thediameter of at least one of the apertures 160 a may be separated fromthe diameter of at least one of the apertures 160 b by the distance A.The diameter of each of the apertures 160 b may also be separated fromone another by the distance A. A center of one of the apertures 160 cmay be separated from a center of another of the apertures 160 c in afirst direction by a distance B between about 2.8 millimeters to about3.2 millimeters. In a second direction transverse to the firstdirection, the center of one of the apertures 160 c may be separatedfrom the center of another of the apertures 160 c by a distance Cbetween about 2.8 millimeters to about 3.2 millimeters. As shown inFIGS. 4A-4B, the distance B and the distance C may be increased for theapertures 160 c in the central portion 156 being positioned proximate toor at the border 161 compared to the apertures 160 c positioned awayfrom the border 161.

As shown in FIGS. 4A-4B, the central portion 156 of the base layer 132may be substantially square with each side of the central portion 156having a length D between about 100 millimeters to about 108millimeters. In some embodiments, the length D may be between about 106millimeters to about 108 millimeters. The border 161 of the base layer132 may have a width E between about 4 millimeters to about 11millimeters and may substantially surround the central portion 156 andthe apertures 160 c in the central portion 156. In some embodiments, thewidth E may be between about 9 millimeters to about 10 millimeters. Theperiphery 152 of the base layer 132 may have a width F between about 25millimeters to about 35 millimeters and may substantially surround theborder 161 and the central portion 156. In some embodiments, the width Fmay be between about 26 millimeters to about 28 millimeters. Further,the periphery 152 may have a substantially square exterior with eachside of the exterior having a length G between about 154 millimeters toabout 200 millimeters. In some embodiments, the length G may be betweenabout 176 millimeters to about 184 millimeters. Although FIGS. 4A-4Bdepict the central portion 156, the border 161, and the periphery 152 ofthe base layer 132 as having a substantially square shape, these andother components of the base layer 132 may have any shape to suit aparticular application. Further, the dimensions of the base layer 132 asdescribed herein may be increased or decreased, for example,substantially in proportion to one another to suit a particularapplication. The use of the dimensions in the proportions describedabove may enhance the cosmetic appearance of a tissue site. For example,these proportions may provide a surface area for the base layer 132,regardless of shape, that is sufficiently smooth to enhance the movementand proliferation of epithelial cells at the tissue site 104, and reducethe likelihood of granulation tissue in-growth into the dressing 124.

The base layer 132 may be a soft, pliable material suitable forproviding a fluid seal with the tissue site 104 as described herein. Forexample, the base layer 132 may comprise a silicone gel, a softsilicone, hydrocolloid, hydrogel, polyurethane gel, polyolefin gel,hydrogenated styrenic copolymer gels, a foamed gel, a soft closed cellfoam such as polyurethanes and polyolefins coated with an adhesivedescribed below, polyurethane, polyolefin, or hydrogenated styreniccopolymers. The base layer 132 may have a thickness between about 500microns (μm) and about 1000 microns (μm). In some embodiments, the baselayer 132 has a stiffness between about 5 Shore OO and about 80 ShoreOO. The base layer 132 may be comprised of hydrophobic or hydrophilicmaterials.

In some embodiments (not shown), the base layer 132 may be ahydrophobic-coated material. For example, the base layer 132 may beformed by coating a spaced material, such as, for example, woven,nonwoven, molded, or extruded mesh with a hydrophobic material. Thehydrophobic material for the coating may be a soft silicone, forexample. In this manner, the adhesive 136 may extend through openings inthe spaced material analogous to the apertures 160 described below.

The adhesive 136 may be in fluid communication with the apertures 160 inat least the periphery 152 of the base layer 132. In this manner, theadhesive 136 may be in fluid communication with the tissue surroundingthe tissue site 104 through the apertures 160 in the base layer 132. Asdescribed below and shown in FIG. 3, the adhesive 136 may extend or bepressed through the plurality of apertures 160 to contact the epidermis106 for securing the dressing 124 to, for example, the tissuesurrounding the tissue site 104. The apertures 160 may providesufficient contact of the adhesive 136 to the epidermis 106 to securethe dressing 124 about the tissue site 104. However, the configurationof the apertures 160 and the adhesive 136, described below, may permitrelease and repositioning of the dressing 124 about the tissue site 104.

At least one of the apertures 160 a in the periphery 152 of the baselayer 132 may be positioned at the edges 159 of the periphery 152 andmay have an interior cut open or exposed at the edges 159 that is influid communication in a lateral direction with the edges 159. Thelateral direction may refer to a direction toward the edges 159 and inthe same plane as the base layer 132. As shown in FIGS. 4A-4B, aplurality of the apertures 160 a in the periphery 152 may be positionedproximate to or at the edges 159 and in fluid communication in a lateraldirection with the edges 159. The apertures 160 a positioned proximateto or at the edges 159 may be spaced substantially equidistant aroundthe periphery 152 as shown in FIGS. 4A-4B. However, in some embodiments,the spacing of the apertures 160 a proximate to or at the edges 159 maybe irregular. The adhesive 136 may be in fluid communication with theedges 159 through the apertures 160 a being exposed at the edges 159. Inthis manner, the apertures 160 a at the edges 159 may permit theadhesive 136 to flow around the edges 159 for enhancing the adhesion ofthe edges 159 around the tissue site 104, for example.

Continuing with FIGS. 4A-4B, the apertures 160 b at the corners 158 ofthe periphery 152 may be smaller than the apertures 160 a in otherportions of the periphery 152 as described above. For a given geometryof the corners 158, the smaller size of the apertures 160 b compared tothe apertures 160 a may maximize the surface area of the adhesive 136exposed and in fluid communication through the apertures 160 b at thecorners 158. For example, as shown in FIGS. 4A-4B, the edges 159 mayintersect at substantially a right angle, or about 90 degrees, to definethe corners 158. Also as shown, the corners 158 may have a radius ofabout 10 millimeters. Three of the apertures 160 b having a diameterbetween about 7.75 millimeters to about 8.75 millimeters may bepositioned in a triangular configuration at the corners 158 to maximizethe exposed surface area for the adhesive 136. The size and number ofthe apertures 160 b in the corners 158 may be adjusted as necessary,depending on the chosen geometry of the corners 158, to maximize theexposed surface area of the adhesive 136 as described above. Further,the apertures 160 b at the corners 158 may be fully housed within thebase layer 132, substantially precluding fluid communication in alateral direction exterior to the corners 158. The apertures 160 b atthe corners 158 being fully housed within the base layer 132 maysubstantially preclude fluid communication of the adhesive 136 exteriorto the corners 159, and may provide improved handling of the dressing124 during deployment at the tissue site 104. Further, the exterior ofthe corners 158 being substantially free of the adhesive 136 mayincrease the flexibility of the corners 158 to enhance comfort.

Similar to the apertures 160 b in the corners 158, any of the apertures160 may be adjusted in size and number to maximize the surface area ofthe adhesive 136 in fluid communication through the apertures 160 for aparticular application or geometry of the base layer 132. For example,in some embodiments (not shown) the apertures 160 b, or apertures ofanother size, may be positioned in the periphery 152 and at the border161. Similarly, the apertures 160 b, or apertures of another size, maybe positioned as described above in other locations of the base layer132 that may have a complex geometry or shape.

The adhesive 136 may be a medically-acceptable adhesive. The adhesive136 may also be flowable. For example, the adhesive 136 may comprise anacrylic adhesive, rubber adhesive, high-tack silicone adhesive,polyurethane, or other adhesive substance. In some embodiments, theadhesive 136 may be a pressure-sensitive adhesive comprising an acrylicadhesive with coating weight of 15 grams/m² (gsm) to 70 grams/m² (gsm).The adhesive 136 may be a layer having substantially the same shape asthe periphery 152 of the base layer 132 as shown in FIG. 4A. In someembodiments, the layer of the adhesive 136 may be continuous ordiscontinuous. Discontinuities in the adhesive 136 may be provided byapertures (not shown) in the adhesive 136. The apertures in the adhesive136 may be formed after application of the adhesive 136 or by coatingthe adhesive 136 in patterns on a carrier layer, such as, for example, aside of the sealing member 140 adapted to face the epidermis 106.Further, the apertures in the adhesive 136 may be sized to control theamount of the adhesive 136 extending through the apertures 160 in thebase layer 132 to reach the epidermis 106. The apertures in the adhesive136 may also be sized to enhance the Moisture Vapor Transfer Rate (MVTR)of the dressing 124, described further below.

Factors that may be utilized to control the adhesion strength of thedressing 124 may include the diameter and number of the apertures 160 inthe base layer 132, the thickness of the base layer 132, the thicknessand amount of the adhesive 136, and the tackiness of the adhesive 136.An increase in the amount of the adhesive 136 extending through theapertures 160 generally corresponds to an increase in the adhesionstrength of the dressing 124. A decrease in the thickness of the baselayer 132 generally corresponds to an increase in the amount of adhesive136 extending through the apertures 160. Thus, the diameter andconfiguration of the apertures 160, the thickness of the base layer 132,and the amount and tackiness of the adhesive utilized may be varied toprovide a desired adhesion strength for the dressing 124. For example,the thickness of the base layer 132 may be about 200 microns, theadhesive layer 136 may have a thickness of about 30 microns and atackiness of 2000 grams per 25 centimeter wide strip, and the diameterof the apertures 160 a in the base layer 132 may be about 10millimeters.

In some embodiments, the tackiness of the adhesive 136 may vary indifferent locations of the base layer 132. For example, in locations ofthe base layer 132 where the apertures 160 are comparatively large, suchas the apertures 160 a, the adhesive 136 may have a lower tackiness thanother locations of the base layer 132 where the apertures 160 aresmaller, such as the apertures 160 b and 160 c. In this manner,locations of the base layer 132 having larger apertures 160 and lowertackiness adhesive 136 may have an adhesion strength comparable tolocations having smaller apertures 160 and higher tackiness adhesive136.

Clinical studies have shown that the configuration described herein forthe base layer 132 and the adhesive 136 may reduce the occurrence ofblistering, erythema, and leakage when in use. Such a configuration mayprovide, for example, increased patient comfort and increased durabilityof the dressing 124.

Referring to the embodiment of FIG. 4B, a release liner 162 may beattached to or positioned adjacent to the base layer 132 to protect theadhesive 136 prior to application of the dressing 124 to the tissue site104. Prior to application of the dressing 124 to the tissue site 104,the base layer 132 may be positioned between the sealing member 140 andthe release liner 162. Removal of the release liner 162 may expose thebase layer 132 and the adhesive 136 for application of the dressing 124to the tissue site 104. The release liner 162 may also provide stiffnessto assist with, for example, deployment of the dressing 124. The releaseliner 162 may be, for example, a casting paper, a film, or polyethylene.Further, the release liner 162 may be a polyester material such aspolyethylene terephthalate (PET), or similar polar semi-crystallinepolymer. The use of a polar semi-crystalline polymer for the releaseliner 162 may substantially preclude wrinkling or other deformation ofthe dressing 124. For example, the polar semi-crystalline polymer may behighly orientated and resistant to softening, swelling, or otherdeformation that may occur when brought into contact with components ofthe dressing 124, or when subjected to temperature or environmentalvariations, or sterilization. Further, a release agent may be disposedon a side of the release liner 162 that is configured to contact thebase layer 132. For example, the release agent may be a silicone coatingand may have a release factor suitable to facilitate removal of therelease liner 162 by hand and without damaging or deforming the dressing124. In some embodiments, the release agent may be flourosilicone. Inother embodiments, the release liner 162 may be uncoated or otherwiseused without a release agent.

Continuing with FIGS. 1-4B, the sealing member 140 has a periphery 164and a central portion 168. The sealing member 140 may additionallyinclude an aperture 170, as described below. The periphery 164 of thesealing member 140 may be positioned proximate to the periphery 152 ofthe base layer 132 such that the central portion 168 of the sealingmember 140 and the central portion 156 of the base layer 132 define anenclosure 172. The adhesive 136 may be positioned at least between theperiphery 164 of the sealing member 140 and the periphery 152 of thebase layer 132. The sealing member 140 may cover the tissue site 104 andthe interface manifold 120 to provide a fluid seal and a sealed space174 between the tissue site 104 and the sealing member 140 of thedressing 124. Further, the sealing member 140 may cover other tissue,such as a portion of the epidermis 106, surrounding the tissue site 104to provide the fluid seal between the sealing member 140 and the tissuesite 104. In some embodiments, a portion of the periphery 164 of thesealing member 140 may extend beyond the periphery 152 of the base layer132 and into direct contact with tissue surrounding the tissue site 104.In other embodiments, the periphery 164 of the sealing member 140, forexample, may be positioned in contact with tissue surrounding the tissuesite 104 to provide the sealed space 174 without the base layer 132.Thus, the adhesive 136 may also be positioned at least between theperiphery 164 of the sealing member 140 and tissue, such as theepidermis 106, surrounding the tissue site 104. The adhesive 136 may bedisposed on a surface of the sealing member 140 adapted to face thetissue site 104 and the base layer 132.

The sealing member 140 may be formed from any material that allows for afluid seal. A fluid seal is a seal adequate to maintain reduced pressureat a desired site given the particular reduced pressure source or systeminvolved. The sealing member 140 may comprise, for example, one or moreof the following materials: hydrophilic polyurethane; cellulosics;hydrophilic polyamides; polyvinyl alcohol; polyvinyl pyrrolidone;hydrophilic acrylics; hydrophilic silicone elastomers; an INSPIRE 2301material from Expopack Advanced Coatings of Wrexham, United Kingdomhaving, for example, an MVTR (inverted cup technique) of 14400 g/m²/24hours and a thickness of about 30 microns; a thin, uncoated polymerdrape; natural rubbers; polyisoprene; styrene butadiene rubber;chloroprene rubber; polybutadiene; nitrile rubber; butyl rubber;ethylene propylene rubber; ethylene propylene diene monomer;chlorosulfonated polyethylene; polysulfide rubber; polyurethane (PU);EVA film; co-polyester; silicones; a silicone drape; a 3M Tegaderm®drape; a polyurethane (PU) drape such as one available from AveryDennison Corporation of Pasadena, Calif.; polyether block polyamidecopolymer (PEBAX), for example, from Arkema, France; Expopack 2327; orother appropriate material.

The sealing member 140 may be vapor permeable and liquid impermeable,thereby allowing vapor and inhibiting liquids from exiting the sealedspace 174 provided by the dressing 124. In some embodiments, the sealingmember 140 may be a flexible, breathable film, membrane, or sheet havinga high MVTR of, for example, at least about 300 g/m² per 24 hours. Inother embodiments, a low or no vapor transfer drape might be used. Thesealing member 140 may comprise a range of medically suitable filmshaving a thickness between about 15 microns (μm) to about 50 microns(μm).

The fluid management assembly 144 may be disposed in the enclosure 172and may include a first wicking layer 176, a second wicking layer 180,and an absorbent layer 184. The absorbent layer 184 may be positioned influid communication between the first wicking layer 176 and the secondwicking layer 180. The first wicking layer 176 may have a grainstructure (not shown) adapted to wick fluid along a surface of the firstwicking layer 176. Similarly, the second wicking layer 180 may have agrain structure (not shown) adapted to wick fluid along a surface of thesecond wicking layer 180. For example, the first wicking layer 176 andthe second wicking layer 180 may wick or otherwise transport fluid in alateral direction along the surfaces of the first wicking layer 176 andthe second wicking layer 180, respectively. The surfaces of the firstwicking layer 176 and the second wicking layer 180 may be normalrelative to the thickness of each of the first wicking layer 176 and thesecond wicking layer 180. The wicking of fluid along the first wickinglayer 176 and the second wicking layer 180 may enhance the distributionof the fluid over a surface area of the absorbent layer 184 that mayincrease absorbent efficiency and resist fluid blockages. Fluidblockages may be caused by, for example, fluid pooling in a particularlocation in the absorbent layer 184 rather than being distributed moreuniformly across the absorbent layer 184. The laminate combination ofthe first wicking layer 176, the second wicking layer 180, and theabsorbent layer 184 may be adapted as described above to maintain anopen structure, resistant to blockage, capable of maintaining fluidcommunication with, for example, the tissue site 104.

Referring to the embodiments of the fluid management assembly 144depicted in FIGS. 1, 2, 5, and 6, a peripheral portion 186 of the firstwicking layer 176 may be coupled to a peripheral portion 187 of thesecond wicking layer 180 to define a wicking layer enclosure 188 betweenthe first wicking layer 176 and the second wicking layer 180. In someexemplary embodiments, the wicking layer enclosure 188 may surround orotherwise encapsulate the absorbent layer 184 between the first wickinglayer 176 and the second wicking layer 180.

Referring specifically to FIGS. 5 and 6, the fluid management assembly144 may include, without limitation, any number of wicking layers andabsorbent layers as desired for treating a particular tissue site. Forexample, the absorbent layer 184 may be a plurality of absorbent layers184 positioned in fluid communication between the first wicking layer176 and the second wicking layer 180 as described above. Further, asdepicted in FIG. 6, at least one intermediate wicking layer 189 may bedisposed in fluid communication between the plurality of absorbentlayers 184. Similar to the absorbent layer 184 described above, theplurality of absorbent layers 184 and the at least one intermediatewicking layer 189 may be positioned within the wicking layer enclosure188. In some embodiments, the absorbent layer 184 may be disposedbetween the sealing member 140 and the interface manifold 120, and thefirst wicking layer 176 and the second wicking layer 180 may be omitted.

In the embodiments of FIGS. 5 and 6, sides 184 a of the absorbent layers184 may remain in fluid communication with one another for enhancingefficiency. Similarly, in the embodiment of FIG. 6, sides 189 a of theat least one intermediate wicking layer 189 may remain in fluidcommunication with one another and with the sides 184 a of the absorbentlayers 184. Further, including additional absorbent layers 184 mayincrease the absorbent mass of the fluid management assembly 144 andgenerally provide greater fluid capacity. However, for a given absorbentmass, multiple light coat-weight absorbent layers 184 may be utilizedrather than a single heavy coat-weight absorbent layer 184 to provide agreater absorbent surface area for further enhancing the absorbentefficiency.

In some embodiments, the absorbent layer 184 may be a hydrophilicmaterial adapted to absorb fluid from, for example, the tissue site 104.Materials suitable for the absorbent layer 184 may include Luquafleece®material, Texsus FP2326, BASF 402C, Technical Absorbents 2317 availablefrom Technical Absorbents (www.techabsorbents.com), sodium polyacrylatesuper absorbers, cellulosics (carboxy methyl cellulose and salts such assodium CMC), or alginates. Materials suitable for the first wickinglayer 176 and the second wicking layer 180 may include any materialhaving a grain structure capable of wicking fluid as described herein,such as, for example, Libeltex TDL2 80 gsm.

The fluid management assembly 144 may be a pre-laminated structuremanufactured at a single location or individual layers of materialstacked upon one another as described above. Individual layers of thefluid management assembly 144 may be bonded or otherwise secured to oneanother without adversely affecting fluid management by, for example,utilizing a solvent or non-solvent adhesive, or by thermal welding.Further, the fluid management assembly 144 may be coupled to the border161 of the base layer 132 in any suitable manner, such as, for example,by a weld or an adhesive. The border 161 being free of the apertures 160as described above may provide a flexible barrier between the fluidmanagement assembly 144 and the tissue site 104 for enhancing comfort.

In some embodiments, the enclosure 172 defined by the base layer 132 andthe sealing member 140 may include an anti-microbial layer 190. Theaddition of the anti-microbial layer 190 may reduce the probability ofexcessive bacterial growth within the dressing 124 to permit thedressing 124 to remain in place for an extended period. Theanti-microbial layer 190 may be, for example, an additional layerincluded as a part of the fluid management assembly 144 as depicted inFIGS. 1 and 2, or a coating of an anti-microbial agent disposed in anysuitable location within the dressing 124. The anti-microbial layer 190may be comprised of elemental silver or similar compound, for example.In some embodiments, the anti-microbial agent may be formulated in anysuitable manner into other components of the dressing 124.

Referring to FIGS. 1, 2, and 7, the conduit interface 148 may bepositioned proximate to the sealing member 140 and in fluidcommunication with the dressing 124 through the aperture 170 in thesealing member 140 to provide reduced pressure from the reduced-pressuresource 128 to the dressing 124. Specifically, the conduit interface 148may be positioned in fluid communication with the enclosure 172 of thedressing 124. The conduit interface 148 may also be positioned in fluidcommunication with the optional interface manifold 120. As shown, anoptional liquid trap 192 may be positioned in fluid communicationbetween the dressing 124 and the reduced-pressure source 128. The liquidtrap 192 may be any suitable containment device having a sealed internalvolume capable of retaining liquid, such as condensate or other liquids,as described below.

The conduit interface 148 may comprise a medical-grade, soft polymer orother pliable material. As non-limiting examples, the conduit interface148 may be formed from polyurethane, polyethylene, polyvinyl chloride(PVC), fluorosilicone, or ethylene-propylene, etc. In some illustrative,non-limiting embodiments, conduit interface 148 may be molded fromDEHP-free PVC. The conduit interface 148 may be formed in any suitablemanner such as by molding, casting, machining, or extruding. Further,the conduit interface 148 may be formed as an integral unit or asindividual components and may be coupled to the dressing 124 by, forexample, adhesive or welding.

In some embodiments, the conduit interface 148 may be formed of anabsorbent material having absorbent and evaporative properties. Theabsorbent material may be vapor permeable and liquid impermeable,thereby being configured to permit vapor to be absorbed into andevaporated from the material through permeation while inhibitingpermeation of liquids. The absorbent material may be, for example, ahydrophilic polymer such as a hydrophilic polyurethane. Although theterm hydrophilic polymer may be used in the illustrative embodimentsthat follow, any absorbent material having the properties describedherein may be suitable for use in the system 102. Further, the absorbentmaterial or hydrophilic polymer may be suitable for use in variouscomponents of the system 102 as described herein.

The use of such a hydrophilic polymer for the conduit interface 148 maypermit liquids in the conduit interface 148 to evaporate, or otherwisedissipate, during operation. For example, the hydrophilic polymer mayallow the liquid to permeate or pass through the conduit interface 148as vapor, in a gaseous phase, and evaporate into the atmosphere externalto the conduit interface 148. Such liquids may be, for example,condensate or other liquids. Condensate may form, for example, as aresult of a decrease in temperature within the conduit interface 148, orother components of the system 102, relative to the temperature at thetissue site 104. Removal or dissipation of liquids from the conduitinterface 148 may increase visual appeal and prevent odor. Further, suchremoval of liquids may also increase efficiency and reliability byreducing blockages and other interference with the components of thesystem 102.

Similar to the conduit interface 148, the liquid trap 192, and othercomponents of the system 102 described herein, may also be formed of anabsorbent material or a hydrophilic polymer. The absorptive andevaporative properties of the hydrophilic polymer may also facilitateremoval and dissipation of liquids residing in the liquid trap 192, andother components of the system 102, by evaporation. Such evaporation mayleave behind a substantially solid or gel-like waste. The substantiallysolid or gel-like waste may be cheaper to dispose than liquids,providing a cost savings for operation of the system 102. Thehydrophilic polymer may be used for other components in the system 102where the management of liquids is beneficial.

In some embodiments, the absorbent material or hydrophilic polymer mayhave an absorbent capacity in a saturated state that is substantiallyequivalent to the mass of the hydrophilic polymer in an unsaturatedstate. The hydrophilic polymer may be fully saturated with vapor in thesaturated state and substantially free of vapor in the unsaturatedstate. In both the saturated state and the unsaturated state, thehydrophilic polymer may retain substantially the same physical,mechanical, and structural properties. For example, the hydrophilicpolymer may have a hardness in the unsaturated state that issubstantially the same as a hardness of the hydrophilic polymer in thesaturated state. The hydrophilic polymer and the components of thesystem 102 incorporating the hydrophilic polymer may also have a sizethat is substantially the same in both the unsaturated state and thesaturated state. Further, the hydrophilic polymer may remain dry, coolto the touch, and pneumatically sealed in the saturated state and theunsaturated state. The hydrophilic polymer may also remain substantiallythe same color in the saturated state and the unsaturated state. In thismanner, this hydrophilic polymer may retain sufficient strength andother physical properties to remain suitable for use in the system 102.An example of such a hydrophilic polymer is offered under the trade nameTechophilic HP-93A-100, available from The Lubrizol Corporation ofWickliffe, Ohio, United States. Techophilic HP-93A-100 is an absorbenthydrophilic thermoplastic polyurethane capable of absorbing 100% of theunsaturated mass of the polyurethane in water and having a durometer orShore Hardness of about 83 Shore A.

The conduit interface 148 may carry an odor filter 194 adapted tosubstantially preclude the passage of odors from the tissue site 104 outof the sealed space 174. Further, the conduit interface 148 may carry aprimary hydrophobic filter 195 adapted to substantially preclude thepassage of liquids out of the sealed space 174. The odor filter 194 andthe primary hydrophobic filter 195 may be disposed in the conduitinterface 148 or other suitable location such that fluid communicationbetween the reduced-pressure source 128, or optional therapy unit 130,and the dressing 124 is provided through the odor filter 194 and theprimary hydrophobic filter 195. In some embodiments, the odor filter 194and the primary hydrophobic filter 195 may be secured within the conduitinterface 148 in any suitable manner, such as by adhesive or welding. Inother embodiments, the odor filter 194 and the primary hydrophobicfilter 195 may be positioned in any exit location in the dressing 124that is in fluid communication with the atmosphere, the reduced-pressuresource 128, or the optional therapy unit 130. The odor filter 194 mayalso be positioned in any suitable location in the system 102 that is influid communication with the tissue site 104.

The odor filter 194 may be comprised of a carbon material in the form ofa layer or particulate. For example, the odor filter 194 may comprise awoven carbon cloth filter such as those manufactured by ChemvironCarbon, Ltd. of Lancashire, United Kingdom (www.chemvironcarbon.com).The primary hydrophobic filter 195 may be comprised of a material thatis liquid impermeable and vapor permeable. For example, the primaryhydrophobic filter 195 may comprise a material manufactured under thedesignation MMT-314 by W. L. Gore & Associates, Inc. of Newark, Del.,United States, or similar materials. The primary hydrophobic filter 195may be provided in the form of a membrane or layer.

Continuing with FIGS. 1, 2, and 7, the reduced-pressure source 128provides reduced pressure to the dressing 124 and the sealed space 174.The reduced-pressure source 128 may be any suitable device for providingreduced pressure, such as, for example, a vacuum pump, wall suction,hand pump, or other source. As shown in FIG. 1, the reduced-pressuresource 128 may be a component of the therapy unit 130. The therapy unit130 may include control circuitry and sensors, such as a pressuresensor, that may be configured to monitor reduced pressure at the tissuesite 104. The therapy unit 130 may also be configured to control theamount of reduced pressure from the reduced-pressure source 128 beingapplied to the tissue site 104 according to a user input and areduced-pressure feedback signal received from the tissue site 104.

As used herein, “reduced pressure” generally refers to a pressure lessthan the ambient pressure at a tissue site being subjected to treatment.Typically, this reduced pressure will be less than the atmosphericpressure. The reduced pressure may also be less than a hydrostaticpressure at a tissue site. Unless otherwise indicated, values ofpressure stated herein are gauge pressures. While the amount and natureof reduced pressure applied to a tissue site will typically varyaccording to the application, the reduced pressure will typically bebetween −5 mm Hg and −500 mm Hg, and more typically in a therapeuticrange between −100 mm Hg and −200 mm Hg.

The reduced pressure delivered may be constant or varied (patterned orrandom), and may be delivered continuously or intermittently. Althoughthe terms “vacuum” and “negative pressure” may be used to describe thepressure applied to the tissue site, the actual pressure applied to thetissue site may be more than the pressure normally associated with acomplete vacuum. Consistent with the use herein, an increase in reducedpressure or vacuum pressure typically refers to a relative reduction inabsolute pressure. An increase in reduced pressure corresponds to areduction in pressure (more negative relative to ambient pressure) and adecrease in reduced pressure corresponds to an increase in pressure(less negative relative to ambient pressure).

As shown in FIG. 7, a conduit 196 having an internal lumen 197 may becoupled in fluid communication between the reduced-pressure source 128and the dressing 124. The internal lumen 197 may have an internaldiameter between about 0.5 millimeters to about 3.0 millimeters. Morespecifically, the internal diameter of the internal lumen 197 may bebetween about 1 millimeter to about 2 millimeters. The conduit interface148 may be coupled in fluid communication with the dressing 124 andadapted to connect between the conduit 196 and the dressing 124 forproviding fluid communication with the reduced-pressure source 128. Theconduit interface 148 may be fluidly coupled to the conduit 196 in anysuitable manner, such as, for example, by an adhesive, solvent ornon-solvent bonding, welding, or interference fit. The aperture 170 inthe sealing member 140 may provide fluid communication between thedressing 124 and the conduit interface 148. Specifically, the conduitinterface 148 may be in fluid communication with the enclosure 172 orthe sealed space 174 through the aperture 170 in the sealing member 140.In some embodiments, the conduit 196 may be inserted into the dressing124 through the aperture 170 in the sealing member 140 to provide fluidcommunication with the reduced-pressure source 128 without use of theconduit interface 148. The reduced-pressure source 128 may also bedirectly coupled in fluid communication with the dressing 124 or thesealing member 140 without use of the conduit 196. The conduit 196 maybe, for example, a flexible polymer tube. A distal end of the conduit196 may include a coupling 198 for attachment to the reduced-pressuresource 128.

The conduit 196 may have a secondary hydrophobic filter 199 disposed inthe internal lumen 197 such that fluid communication between thereduced-pressure source 128 and the dressing 124 is provided through thesecondary hydrophobic filter 199. The secondary hydrophobic filter 199may be, for example, a porous, sintered polymer cylinder sized to fitthe dimensions of the internal lumen 197 to substantially precludeliquid from bypassing the cylinder. The secondary hydrophobic filter 199may also be treated with an absorbent material adapted to swell whenbrought into contact with liquid to block the flow of the liquid. Thesecondary hydrophobic filter 199 may be positioned at any locationwithin the internal lumen 197. However, positioning the secondaryhydrophobic filter 199 within the internal lumen 197 closer toward thereduced-pressure source 128, rather than the dressing 124, may allow auser to detect the presence of liquid in the internal lumen 197.

In some embodiments, the conduit 196 and the coupling 198 may be formedof an absorbent material or a hydrophilic polymer as described above forthe conduit interface 148. In this manner, the conduit 196 and thecoupling 198 may permit liquids in the conduit 196 and the coupling 198to evaporate, or otherwise dissipate, as described above for the conduitinterface 148. The conduit 196 and the coupling 198 may be, for example,molded from the hydrophilic polymer separately, as individualcomponents, or together as an integral component. Further, a wall of theconduit 196 defining the internal lumen 197 may be extruded from thehydrophilic polymer. The conduit 196 may be less than about 1 meter inlength, but may have any length to suit a particular application. Morespecifically, a length of about 1 foot or 304.8 millimeters may provideenough absorbent and evaporative surface area to suit many applications,and may provide a cost savings compared to longer lengths. If anapplication requires additional length for the conduit 196, theabsorbent hydrophilic polymer may be coupled in fluid communication witha length of conduit formed of a non-absorbent hydrophobic polymer toprovide additional cost savings.

Referring now to FIG. 8, FIG. 8 depicts the dressing 124 including afluid management assembly 244 suitable for use with the dressing 124 andthe system 102. The fluid management assembly 244 may include a firstwicking layer 276, a second wicking layer 280, and an absorbent layer284 comprised of substantially the same materials and properties asthose described above in connection with the fluid management assembly144. Thus, the first wicking layer 276, the second wicking layer 280,and the absorbent layer 284 are analogous to the first wicking layer176, the second wicking layer 180, and the absorbent layer 184,respectively.

In the fluid management assembly 244, the second wicking layer 280 mayhave a peripheral portion 287. The second wicking layer 280 and theperipheral portion 287 of the second wicking layer 280 may be positionedin contact with the sealing member 140. The absorbent layer 284 may havea peripheral portion 285 extending beyond the peripheral portion 287 ofthe second wicking layer 280. The absorbent layer 284 may be positionedadjacent to or proximate to the second wicking layer 280 such that theperipheral portion 285 of the absorbent layer 284 is in contact with thesealing member 140 surrounding the peripheral portion 287 of the secondwicking layer 280. Similarly, the first wicking layer 276 may have aperipheral portion 286 extending beyond the peripheral portion 285 ofthe absorbent layer 284. The first wicking layer 276 may be positionedadjacent to or proximate to the absorbent layer 284 such that theperipheral portion 286 of the first wicking layer 276 is in contact withthe sealing member 140 surrounding the peripheral portion 285 of theabsorbent layer 284. Further, the first wicking layer 276 may bepositioned adjacent to or proximate to the base layer 132. Thus, atleast the peripheral portion 287, the peripheral portion 285, and theperipheral portion 286 in contact with the sealing member 140 may becoupled to the sealing member 140, such as, for example, by an adhesivecoating disposed on a surface of the sealing member 140 facing the baselayer 132. The adhesive coating may be analogous to the adhesive 136being applied across the surface of the sealing member 140 facing thebase layer 132. The second wicking layer 280, the absorbent layer 284,and the first wicking layer 276 may respectively have increasing surfaceareas to enhance contact with the adhesive coating described above. Inother embodiments, the fluid management assembly 244 may include anynumber of absorbent layers and wicking layers for treating a particulartissue site.

In operation of the system 102 according to some illustrativeembodiments, the interface manifold 120 may be disposed against orproximate to the tissue site 104. The dressing 124 may then be appliedover the interface manifold 120 and the tissue site 104 to form thesealed space 174. Specifically, the base layer 132 may be appliedcovering the interface manifold 120 and the tissue surrounding thetissue site 104. The materials described above for the base layer 132have a tackiness that may hold the dressing 124 initially in position.The tackiness may be such that if an adjustment is desired, the dressing124 may be removed and reapplied. Once the dressing 124 is in thedesired position, a force may be applied, such as by hand pressing, on aside of the sealing member 140 opposite the tissue site 104. The forceapplied to the sealing member 140 may cause at least some portion of theadhesive 136 to penetrate or extend through the plurality of apertures160 and into contact with tissue surrounding the tissue site 104, suchas the epidermis 106, to releaseably adhere the dressing 124 about thetissue site 104. In this manner, the configuration of the dressing 124described above may provide an effective and reliable seal againstchallenging anatomical surfaces, such as an elbow or heal, at and aroundthe tissue site 104. Further, the dressing 124 permits re-application orre-positioning to, for example, correct air leaks caused by creases andother discontinuities in the dressing 124 and the tissue site 104. Theability to rectify leaks may increase the reliability of the therapy andreduce power consumption.

As the dressing 124 comes into contact with fluid from the tissue site104, the fluid moves through the apertures 160 toward the fluidmanagement assembly 144, 244. The fluid management assembly 144, 244wicks or otherwise moves the fluid through the interface manifold 120and away from the tissue site 104. As described above, the interfacemanifold 120 may be adapted to communicate fluid from the tissue site104 rather than store the fluid. Thus, the fluid management assembly144, 244 may be more absorbent than the interface manifold 120. Thefluid management assembly 144, 244 being more absorbent than theinterface manifold 120 provides an absorbent gradient through thedressing 124 that attracts fluid from the tissue site 104 or theinterface manifold 120 to the fluid management assembly 144, 244. Thus,in some embodiments, the fluid management assembly 144, 244 may beadapted to wick, pull, draw, or otherwise attract fluid from the tissuesite 104 through the interface manifold 120. In the fluid managementassembly 144, 244, the fluid initially comes into contact with the firstwicking layer 176, 276. The first wicking layer 176, 276 may distributethe fluid laterally along the surface of the first wicking layer 176,276 as described above for absorption and storage within the absorbentlayer 184, 284. Similarly, fluid coming into contact with the secondwicking layer 180, 280 may be distributed laterally along the surface ofthe second wicking layer 180, 280 for absorption within the absorbentlayer 184, 284.

Referring to FIGS. 9A-9E, in other embodiments, the conduit 196 may be amulti-lumen conduit 302. For example, FIG. 9A depicts an illustrativeembodiment of a multi-lumen conduit 302 a. The multi-lumen conduit 302 amay have an external surface 306, a primary lumen 310, a wall 314, andat least one secondary lumen 318. The wall 314 may carry the primarylumen 310 and the at least one secondary lumen 318. The primary lumen310 may be substantially isolated from fluid communication with the atleast one secondary lumen 318 along the length of the multi-lumenconduit 302 a. Although shown in FIG. 9A as having a substantiallycircular cross-section, the external surface 306 of the multi-lumenconduit 302 a may have any shape to suit a particular application. Thewall 314 of the multi-lumen conduit 302 a may have a thickness betweenthe primary lumen 310 and the external surface 306. As depicted in FIG.9A, the at least one secondary lumen 318 may be four secondary lumens318 carried by the wall 314 substantially parallel to the primary lumen310 and about a perimeter of the primary lumen 310. The secondary lumens318 may be separate from one another and substantially isolated fromfluid communication with one another along the length of the multi-lumenconduit 302 a. Further, the secondary lumens 318 may be separate fromthe primary lumen 310 and substantially isolated from fluidcommunication with the primary lumen 310. The secondary lumens 318 mayalso be positioned concentric relative to the primary lumen 310 andsubstantially equidistant about the perimeter of the primary lumen 310.Although FIG. 9A depicts four secondary lumens 318, any number ofsecondary lumens 318 may be provided and positioned in any suitablemanner for a particular application.

Similar to the internal lumen 197 of the conduit 196, the primary lumen310 may be coupled in fluid communication between the reduced-pressuresource 128 and the dressing 124 as described above. In some embodiments,the primary lumen 310 may be coupled in fluid communication between theconduit interface 148 and the reduced-pressure source 128. Further,analogous to the internal lumen 197, reduced pressure may be providedthrough the primary lumen 310 from the reduced-pressure source 128 tothe dressing 124. In some embodiments, the primary lumen 310 may beconfigured to extract fluid such as exudate from the tissue site 104.The secondary lumens 318 may be coupled in fluid communication betweenthe therapy unit 130 and the dressing 124. In some embodiments, the atleast one secondary lumen 318 may be coupled in fluid communicationbetween the conduit interface 148 and the therapy unit 130. Further, thesecondary lumens 318 may be in fluid communication with the primarylumen 310 at the dressing 124 and configured to provide areduced-pressure feedback signal from the dressing 124 to the therapyunit 130. For example, the secondary lumens 318 may be in fluidcommunication with the primary lumen 310 at the conduit interface 148 orother component of the dressing 124.

The multi-lumen conduit 302 a may be comprised of an absorbent materialor hydrophilic polymer, such as, for example, the absorbent material orthe hydrophilic polymer described above in connection with the conduitinterface 148, the conduit 196, and the coupling 198. The absorbentmaterial or the hydrophilic polymer may be vapor permeable and liquidimpermeable. In some embodiments, at least a portion of the wall 314 andthe external surface 306 of the multi-lumen conduit 302 a may becomprised of the absorbent material or the hydrophilic polymer. In thismanner, the multi-lumen conduit 302 a may permit liquids, such ascondensate, in the multi-lumen conduit 302 a to evaporate, or otherwisedissipate, as described above. For example, the absorbent material orthe hydrophilic polymer may allow the liquid to pass through themulti-lumen conduit 302 a as vapor, in a gaseous phase, and evaporateinto the atmosphere external to the multi-lumen conduit 302 a. Liquidssuch as exudate from the tissue site 104 may also be evaporated ordissipated through the multi-lumen conduit 302 a in the same manner.This feature may be advantageous when the optional therapy unit 130 isused for monitoring and controlling reduced pressure at the tissue site104. For example, liquid present in the secondary lumens 318 mayinterfere with a reduced-pressure feedback signal being transmitted tothe therapy unit 130 through the secondary lumens 318. The use of thehydrophilic polymer for the multi-lumen conduit 302 a may permit removalof such liquid for enhancing the visual appeal, reliability, andefficiency of the system 102. After evaporation of liquid in themulti-lumen conduit 302 a, other blockages from, for example, desiccatedexudate, solids, or gel-like substances that were carried by theevaporated liquid may be visible for further remediation. Further, theuse of the hydrophilic polymer as described herein may reduce theoccurrence of skin damage caused by moisture buildup between componentsof the system 102, such as the multi-lumen conduit 302 a, and the skinof a patient.

Depicted in FIG. 9B is another illustrative embodiment of a multi-lumenconduit 302 b. Similar to the multi-lumen conduit 302 a, the multi-lumenconduit 302 b may have the external surface 306, the primary lumen 310,the wall 314, and the at least one secondary lumen 318 as describedabove. However, the wall 314 of the multi-lumen conduit 302 b mayinclude a first wall material 314 a and a second wall material 314 b.The first wall material 314 a and the second wall material 314 b may becomprised of different materials to form the wall 314. For example, thefirst wall material 314 a may comprise a substantially non-absorbenthydrophobic polymer, or other material, that is vapor impermeable andliquid impermeable. The first wall material 314 a may completelysurround the primary lumen 310, defining the primary lumen 310 as shownin FIG. 9B. In some embodiments (not shown), the first wall material 314a may be positioned around the primary lumen 310 without completelysurrounding or defining the primary lumen 310. The second wall material314 b may comprise the same absorbent material or hydrophilic polymerdescribed above for the multi-lumen conduit 302 a as being vaporpermeable and liquid impermeable. As shown in FIG. 9B, the second wallmaterial 314 b may be positioned in fluid contact with the at least onesecondary lumen 318. The second wall material 314 b may also define theat least one secondary lumen 318 and at least a portion of the externalsurface 306 of the multi-lumen conduit 302 b. In some embodiments (notshown), the second wall material 314 b may substantially surround the atleast one secondary lumen 318 without completely defining the secondarylumen 318.

Continuing with FIG. 9B, the first wall material 314 a may besubstantially concentric about the primary lumen 310, and the secondwall material 314 b may be substantially concentric about and contiguouswith the first wall material 314 a. The first wall material 314 a andthe second wall material 314 b may be molded, co-extruded, or otherwisecombined with one another in any suitable manner to form the wall 314.The wall 314, including the first wall material 314 a and the secondwall material 314 b, may provide a cost savings while retaining theabsorbent and evaporative properties of the hydrophilic polymer forremediating liquid in the multi-lumen conduit 302 b and the at least onesecondary lumen 318. Further, the use of the first wall material 314 aas described herein may provide sufficient strength and other physicalproperties for the multi-lumen conduit 302 b to remain serviceable underreduced pressure in the system 102 without regard to the physicalproperties of second wall material 314 b. For example, the use of anon-absorbent hydrophobic polymer for the first wall material 314 a maypermit the use of absorbent hydrophilic polymers for the second wallmaterial 314 b that may not otherwise have sufficient strength for useunder reduced pressure in the system 102.

The first wall material 314 a may be combined with the second wallmaterial 314 b to form the wall 314 in various configurations forremediating liquid in the multi-lumen conduit 302 and the at least onesecondary lumen 318. For example, referring to FIG. 9C, depicted is anillustrative embodiment of a multi-lumen conduit 302 c. Similar to themulti-lumen conduits 302 a and 302 b, the multi-lumen conduit 302 c mayhave the external surface 306, the primary lumen 310, the wall 314, andthe at least one secondary lumen 318. As shown in FIG. 9C, the wall 314of the multi-lumen conduit 302 c may include the first wall material 314a positioned around the primary lumen 310 and the second wall material314 b disposed in separate portions around each of the secondary lumens318. In this configuration, for example, the external surface 306 maycomprise both the first wall material 314 a and the second wall material314 b. Also as shown in FIG. 9C, the first wall material 314 a maycompletely surround the primary lumen 310. The second wall material 314b may be disposed as portions separate from one another and separatefrom the primary lumen in a radial configuration about the perimeter ofthe primary lumen 310. However, in some embodiments, the second wallmaterial 314 b may be in fluid contact with the primary lumen 310 andmay form a portion of the external surface 306. The amount of the secondwall material 314 b surrounding the secondary lumens 318 may beincreased or decreased to suit a particular application depending, forexample, on the amount of liquid anticipated to be present and thedesired mechanical properties of the multi-lumen conduit 302 c.

Continuing with FIG. 9C, the first wall material 314 a may have areceptor 320 configured to receive the second wall material 314 b. Thesecond wall material 314 b surrounding the secondary lumens 318 may havea shape corresponding to the receptor 320 in the first wall material 314a. For example, each portion of the second wall material 314 b may havea taper 321 a configured to engage a corresponding taper 321 b of thereceptor 320. The taper 321 b may be oriented opposite the taper 321 a.As shown in FIG. 9C, the taper 321 b of the receptor 320 may taper fromthe external surface 306 to a smaller dimension toward the primary lumen310. The taper 321 a may have a taper opposite the direction of thetaper 321 b described above such that the taper 321 b is configured toreceive and engage the taper 321 a.

In some embodiments (not shown), the taper 321 a of the second wallmaterial 314 b may taper from the external surface 306 to a largerdimension toward the primary lumen 310. The taper 321 b of the receptor320 may have a taper opposite the direction of the taper 321 a describedabove such that the taper 321 b is configured to receive and engage thetaper 321 a. In this configuration, with the taper 321 a of the secondwall material 314 b having a larger dimension toward the primary lumen310, the opposite taper 321 b of the receptor 320 may substantiallypreclude the second wall material 314 b from being pulled away from thereceptor 320 in the first wall material 314 a. The above embodiments forthe tapers 321 a and 321 b are non-limiting. Other shapes andconfigurations are suitable for engaging the first wall material 314 awith the second wall material 314 b, such as, for example, interlockingtabs or other mechanical elements.

The multi-lumen conduit 302 may include other materials andconfigurations for managing liquid in the multi-lumen conduit 302 asdescribed herein. For example, referring to FIG. 9D, depicted is anillustrative embodiment of a multi-lumen conduit 302 d. Similar to themulti-lumen conduits 302 a, 302 b, and 302 c, the multi-lumen conduit302 d may have the external surface 306, the primary lumen 310, the wall314, and the at least one secondary lumen 318. The multi-lumen conduit302 d may additionally include an external absorbent layer 322. Theexternal absorbent layer 322 may be positioned around the wall 314 ofthe multi-lumen conduit 302 d. The external absorbent layer 322 may bepositioned, for example, along the entire length of the multi-lumenconduit 302 d or a portion of the length of the multi-lumen conduit 302d. More specifically, the external absorbent layer 322 may be positionedon a portion of the length of the multi-lumen conduit 302 d proximate tothe dressing 124.

Continuing with FIG. 9D, the wall 314 of the multi-lumen conduit 302 dmay comprise an absorbent material or a hydrophilic polymer, such as theabsorbent material or the hydrophilic polymer described above for themulti-lumen conduit 302 a as being vapor permeable and liquidimpermeable. Although not shown in FIG. 9D, the wall 314 of themulti-lumen conduit 302 d may include the first wall material 314 a andthe second wall material 314 b as described above for FIGS. 9B and 9C.The external absorbent layer 322 may be comprised, for example, of thesame absorbent material or hydrophilic polymer of the wall 314. In someembodiments, the external absorbent layer 322 may be comprised of asecond absorbent material or a second hydrophilic polymer that is vaporpermeable and liquid impermeable. The second absorbent material may havea greater absorbent capacity than the absorbent material or hydrophilicpolymer comprising the wall 314 or the second wall material 314 b. Forexample, the second absorbent material of the external absorbent layer322 may be capable of absorbing more than 100% of the unsaturated massof the second absorbent material in water. In this manner, the externalabsorbent layer 322 may be configured to provide an absorptive gradientincreasing in absorbent capacity away from the primary lumen 310 andtoward the external surface 306. The absorptive gradient may pull, wick,draw, or otherwise attract vapor toward the external surface 306 forevaporation. In some embodiments, the thickness of the wall 314 may bereduced to enhance the passage or permeation of vapor through the wall314 and to the external atmosphere. In embodiments (not shown) includingthe first wall material 314 a and the second wall material 314 b, theexternal absorbent layer 322 may be positioned at least around thesecond wall material 314 b and in fluid contact with the second wallmaterial 314 b.

Continuing with FIG. 9D, the external surface 306 of the multi-lumenconduit 302 d may have any shape to suit a particular application. Forexample, the external surface 306 may have a plurality of protrusions326 and depressions 330 configured to increase the external surface areaof the external surface 306. The increased surface area provided by theprotrusions 326 and depressions 330 may enhance the ability of themulti-lumen conduit 302 d to evaporate liquids.

Referring to FIG. 9E, depicted is an illustrative embodiment of amulti-lumen conduit 302 e having an oblong cross section. Similar to themulti-lumen conduits 302 a, 302 b, 302 c, and 302 d, the multi-lumenconduit 302 e may have the external surface 306, the primary lumen 310,the wall 314, and the at least one secondary lumen 318. However, FIG. 9Edepicts the at least one secondary lumen 318 of the multi-lumen conduit302 e as a single secondary lumen 318 that may be carried by the wall314 beside the primary lumen 310. Such a configuration may provide asubstantially flat, low profile shape that may enhance user comfort andmay increase the flexibility of the multi-lumen conduit 302 e. Forexample, in this configuration, the multi-lumen conduit 302 e may berouted through tight spaces with reduced risk of kinking or blockages offluid communication. Although not depicted, additional lumens may beadded in this substantially flat configuration, laterally disposed fromthe primary lumen 310 and the secondary lumen 318, as necessary to suita particular application.

The above features described in connection with the multi-lumen conduits302 a, 302 b, 302 c, 302 d, and 302 e may be used in combination withone another to suit a particular application. For example, the externalabsorbent layer 322 described in the multi-lumen conduit 302 d may beused in combination with any of the multi-lumen conduits 302 a, 302 b,302 c, and 302 e. Further, any of the multi-lumen conduits 302 a, 302 b,302 c, 302 d, and 302 e may be used with padding (not shown) disposedaround the external surface 306, proximate to the dressing 124, forexample, to enhance user comfort.

Although this specification discloses advantages in the context ofcertain illustrative, non-limiting embodiments, various changes,substitutions, permutations, and alterations may be made withoutdeparting from the scope of the appended claims. Further, any featuredescribed in connection with any one embodiment may also be applicableto any other embodiment.

We claim:
 1. A dressing for treating a tissue site, comprising: a baselayer having a periphery surrounding a central portion and a pluralityof apertures disposed through the periphery and the central portion; anadhesive configured to extend through the apertures in at least theperiphery of the base layer to contact tissue surrounding the tissuesite, at least one of the apertures in a corner of the periphery of thebase layer being configured to expose more of the adhesive for contactwith the tissue than other apertures in the periphery of the base layer;a sealing member having a periphery and a central portion, the peripheryof the sealing member positioned proximate to the periphery of the baselayer, wherein the central portion of the sealing member and the centralportion of the base layer define an enclosure; and at least one wickinglayer disposed in the enclosure.
 2. The dressing of claim 1, wherein theapertures in the periphery of the base layer are larger than theapertures in the central portion of the base layer.
 3. The dressing ofclaim 1, wherein the dressing is adapted to provide a sealed space forreceiving reduced pressure at the tissue site.
 4. The dressing of claim1, further comprising a conduit interface positioned proximate to thesealing member and in fluid communication with the enclosure.
 5. Thedressing of claim 1, further comprising an absorbent layer disposed inthe enclosure.
 6. The dressing of claim 1, wherein the central portionof the base layer is adapted to cover the tissue site and the peripheryof the base layer is adapted to be positioned proximate to tissuesurrounding the tissue site.
 7. The dressing of claim 1, wherein theapertures in the base layer are adapted to be in fluid communicationwith the tissue site and tissue surrounding the tissue site.
 8. Thedressing of claim 1, wherein the base layer is comprised of silicone. 9.The dressing of claim 1, wherein the adhesive is an acrylic adhesive.10. The dressing of claim 1, wherein the sealing member is adapted toprovide a sealed space between the sealing member and the tissue site.11. The dressing of claim 1, wherein the at least one wicking layer hasa grain structure adapted to wick fluid along a surface of the at leastone wicking layer.
 12. The dressing of claim 1, wherein the at least onewicking layer is a first wicking layer and a second wicking layer,wherein the dressing further comprises an absorbent layer positioned influid communication between the first wicking layer and the secondwicking layer, and wherein a peripheral portion of the first wickinglayer is coupled to a peripheral portion of the second wicking layerproviding a wicking layer enclosure surrounding the absorbent layerbetween the first and the second wicking layer.
 13. The dressing ofclaim 12, wherein the absorbent layer is a plurality of absorbentlayers, and wherein the plurality of absorbent layers are positioned influid communication between the first wicking layer and the secondwicking layer.
 14. The dressing of claim 13, further comprising at leastone intermediate wicking layer disposed in fluid communication betweenthe absorbent layers.
 15. The dressing of claim 1, the base layerfurther comprising a border substantially surrounding the centralportion and positioned between the central portion and the periphery,the border being substantially free of the apertures.
 16. The dressingof claim 15, wherein the apertures in the central portion of the baselayer are positioned at the border and away from the border, and whereinthe apertures positioned at the border are separated from one another bya greater distance than the apertures positioned away from the border.17. The dressing of claim 15, the border having a width between about 4millimeters to about 11 millimeters.
 18. The dressing of claim 1,wherein the apertures in the periphery of the base layer have a diameterbetween about 9.8 millimeters to about 10.2 millimeters, and wherein theapertures in the central portion of the base layer have a diameterbetween about 1.8 millimeters to about 2.2 millimeters.
 19. The dressingof claim 1, at least three of the apertures in the corner of theperiphery of the base layer being positioned in a triangularconfiguration and being smaller than other apertures in the periphery ofthe base layer.
 20. The dressing of claim 1, a plurality of theapertures in the periphery of the base layer being positioned at theedge and being fluid communication in a lateral direction with the edge,the apertures positioned at the edge being spaced substantiallyequidistant around the periphery of the base layer, the adhesive influid communication with the edge.
 21. The dressing of claim 1, at leastone of the apertures in the periphery of the base layer being positionedin the corner of the periphery and being substantially precluded fromfluid communication in a lateral direction exterior to the corner, theadhesive being substantially precluded from fluid communication exteriorto the corner.
 22. The dressing of claim 1, wherein a plurality of theapertures in the periphery are positioned along an edge of the peripheryand have an interior exposed at the edge.